docstr: Load the indexes listed in this dataset's image set file.
docstr_tok: ["Load","the","indexes","listed","in","this","dataset","'s","image","set","file","."]
code: def _load_image_set_index(self):
      """
      Load the indexes listed in this dataset's image set file.
      """
      # Example path to image set file:
      # self._devkit_path + /VOCdevkit/VOC2007/ImageSets/Main/val.txt
      image_set_file = os.path.join(
          self._data_path, "ImageSets", "Main", self._image_set + ".txt"
      )
      assert os.path.exists(
          image_set_file
      ), "Path does not exist: {}".format(image_set_file)
      with open(image_set_file) as f:
          image_index = [x.strip() for x in f.readlines()]
      return image_index
  
imports: from __future__ import print_function
  import os, pdb
  import xml.dom.minidom
  import numpy
  import scipy.sparse
  import scipy.io
  import pickle
  import subprocess
  from .imdb import imdb
  from .voc_eval import voc_eval
label_desc: Use image node_id 5 for calling the pascal_voc obj's underlying member method code with example usage: obj._load_image_set_index() and returns: image_index